Using Walk Navigation like Unity and Unreal
I'm not sure about 2.8 but in 2.79 you can activate it by pressing Shift + F this way you'll be able to fly around using W, A, S, D, E(Up), Q(Down); You can also activate gravity by pressing TAB.

Edit: you can also use the Mouse Wheel to change the speed of the movement, Up/Forward to increase, and Down/Backward to decrease it.

after you're done:
 LMB to stay in the same place or RMB to return to the original place.

I hope this solves your problem :)